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KVM: PPC: Paravirtualize SPRG4-7, ESR, PIR, MASn
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This allows additional registers to be accessed by the guest
in PR-mode KVM without trapping.

SPRG4-7 are readable from userspace.  On booke, KVM will sync
these registers when it enters the guest, so that accesses from
guest userspace will work.  The guest kernel, OTOH, must consistently
use either the real registers or the shared area between exits.  This
also applies to the already-paravirted SPRG3.

On non-booke, it's not clear to what extent SPRG4-7 are supported
(they're not architected for book3s, but exist on at least some classic
chips).  They are copied in the get/set regs ioctls, but I do not see any
non-booke emulation.  I also do not see any syncing with real registers
(in PR-mode) including the user-readable SPRG3.  This patch should not
make that situation any worse.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
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Scott Wood authored and Avi Kivity committed Mar 5, 2012
1 parent 940b45e commit b590497
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Showing 15 changed files with 339 additions and 169 deletions.
8 changes: 0 additions & 8 deletions arch/powerpc/include/asm/kvm_e500.h
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Original file line number Diff line number Diff line change
Expand Up @@ -71,14 +71,6 @@ struct kvmppc_vcpu_e500 {
u32 pid[E500_PID_NUM];
u32 svr;

u32 mas0;
u32 mas1;
u32 mas2;
u64 mas7_3;
u32 mas4;
u32 mas5;
u32 mas6;

/* vcpu id table */
struct vcpu_id_table *idt;

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6 changes: 0 additions & 6 deletions arch/powerpc/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -318,18 +318,13 @@ struct kvm_vcpu_arch {
u32 vrsave; /* also USPRG0 */
u32 mmucr;
ulong shadow_msr;
ulong sprg4;
ulong sprg5;
ulong sprg6;
ulong sprg7;
ulong csrr0;
ulong csrr1;
ulong dsrr0;
ulong dsrr1;
ulong mcsrr0;
ulong mcsrr1;
ulong mcsr;
ulong esr;
u32 dec;
u32 decar;
u32 tbl;
Expand All @@ -338,7 +333,6 @@ struct kvm_vcpu_arch {
u32 tsr;
u32 ivor[64];
ulong ivpr;
u32 pir;
u32 pvr;

u32 shadow_pid;
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31 changes: 29 additions & 2 deletions arch/powerpc/include/asm/kvm_para.h
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Original file line number Diff line number Diff line change
Expand Up @@ -33,11 +33,35 @@ struct kvm_vcpu_arch_shared {
__u64 sprg3;
__u64 srr0;
__u64 srr1;
__u64 dar;
__u64 dar; /* dear on BookE */
__u64 msr;
__u32 dsisr;
__u32 int_pending; /* Tells the guest if we have an interrupt */
__u32 sr[16];
__u32 mas0;
__u32 mas1;
__u64 mas7_3;
__u64 mas2;
__u32 mas4;
__u32 mas6;
__u32 esr;
__u32 pir;

/*
* SPRG4-7 are user-readable, so we can only keep these consistent
* between the shared area and the real registers when there's an
* intervening exit to KVM. This also applies to SPRG3 on some
* chips.
*
* This suffices for access by guest userspace, since in PR-mode
* KVM, an exit must occur when changing the guest's MSR[PR].
* If the guest kernel writes to SPRG3-7 via the shared area, it
* must also use the shared area for reading while in kernel space.
*/
__u64 sprg4;
__u64 sprg5;
__u64 sprg6;
__u64 sprg7;
};

#define KVM_SC_MAGIC_R0 0x4b564d21 /* "KVM!" */
Expand All @@ -47,7 +71,10 @@ struct kvm_vcpu_arch_shared {

#define KVM_FEATURE_MAGIC_PAGE 1

#define KVM_MAGIC_FEAT_SR (1 << 0)
#define KVM_MAGIC_FEAT_SR (1 << 0)

/* MASn, ESR, PIR, and high SPRGs */
#define KVM_MAGIC_FEAT_MAS0_TO_SPRG7 (1 << 1)

#ifdef __KERNEL__

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15 changes: 11 additions & 4 deletions arch/powerpc/kernel/asm-offsets.c
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Original file line number Diff line number Diff line change
Expand Up @@ -426,16 +426,23 @@ int main(void)
DEFINE(VCPU_SPRG2, offsetof(struct kvm_vcpu, arch.shregs.sprg2));
DEFINE(VCPU_SPRG3, offsetof(struct kvm_vcpu, arch.shregs.sprg3));
#endif
DEFINE(VCPU_SPRG4, offsetof(struct kvm_vcpu, arch.sprg4));
DEFINE(VCPU_SPRG5, offsetof(struct kvm_vcpu, arch.sprg5));
DEFINE(VCPU_SPRG6, offsetof(struct kvm_vcpu, arch.sprg6));
DEFINE(VCPU_SPRG7, offsetof(struct kvm_vcpu, arch.sprg7));
DEFINE(VCPU_SHARED_SPRG4, offsetof(struct kvm_vcpu_arch_shared, sprg4));
DEFINE(VCPU_SHARED_SPRG5, offsetof(struct kvm_vcpu_arch_shared, sprg5));
DEFINE(VCPU_SHARED_SPRG6, offsetof(struct kvm_vcpu_arch_shared, sprg6));
DEFINE(VCPU_SHARED_SPRG7, offsetof(struct kvm_vcpu_arch_shared, sprg7));
DEFINE(VCPU_SHADOW_PID, offsetof(struct kvm_vcpu, arch.shadow_pid));
DEFINE(VCPU_SHADOW_PID1, offsetof(struct kvm_vcpu, arch.shadow_pid1));
DEFINE(VCPU_SHARED, offsetof(struct kvm_vcpu, arch.shared));
DEFINE(VCPU_SHARED_MSR, offsetof(struct kvm_vcpu_arch_shared, msr));
DEFINE(VCPU_SHADOW_MSR, offsetof(struct kvm_vcpu, arch.shadow_msr));

DEFINE(VCPU_SHARED_MAS0, offsetof(struct kvm_vcpu_arch_shared, mas0));
DEFINE(VCPU_SHARED_MAS1, offsetof(struct kvm_vcpu_arch_shared, mas1));
DEFINE(VCPU_SHARED_MAS2, offsetof(struct kvm_vcpu_arch_shared, mas2));
DEFINE(VCPU_SHARED_MAS7_3, offsetof(struct kvm_vcpu_arch_shared, mas7_3));
DEFINE(VCPU_SHARED_MAS4, offsetof(struct kvm_vcpu_arch_shared, mas4));
DEFINE(VCPU_SHARED_MAS6, offsetof(struct kvm_vcpu_arch_shared, mas6));

/* book3s */
#ifdef CONFIG_KVM_BOOK3S_64_HV
DEFINE(KVM_LPID, offsetof(struct kvm, arch.lpid));
Expand Down
204 changes: 171 additions & 33 deletions arch/powerpc/kernel/kvm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -49,23 +49,17 @@
#define KVM_RT_30 0x03c00000
#define KVM_MASK_RB 0x0000f800
#define KVM_INST_MFMSR 0x7c0000a6
#define KVM_INST_MFSPR_SPRG0 0x7c1042a6
#define KVM_INST_MFSPR_SPRG1 0x7c1142a6
#define KVM_INST_MFSPR_SPRG2 0x7c1242a6
#define KVM_INST_MFSPR_SPRG3 0x7c1342a6
#define KVM_INST_MFSPR_SRR0 0x7c1a02a6
#define KVM_INST_MFSPR_SRR1 0x7c1b02a6
#define KVM_INST_MFSPR_DAR 0x7c1302a6
#define KVM_INST_MFSPR_DSISR 0x7c1202a6

#define KVM_INST_MTSPR_SPRG0 0x7c1043a6
#define KVM_INST_MTSPR_SPRG1 0x7c1143a6
#define KVM_INST_MTSPR_SPRG2 0x7c1243a6
#define KVM_INST_MTSPR_SPRG3 0x7c1343a6
#define KVM_INST_MTSPR_SRR0 0x7c1a03a6
#define KVM_INST_MTSPR_SRR1 0x7c1b03a6
#define KVM_INST_MTSPR_DAR 0x7c1303a6
#define KVM_INST_MTSPR_DSISR 0x7c1203a6

#define SPR_FROM 0
#define SPR_TO 0x100

#define KVM_INST_SPR(sprn, moveto) (0x7c0002a6 | \
(((sprn) & 0x1f) << 16) | \
(((sprn) & 0x3e0) << 6) | \
(moveto))

#define KVM_INST_MFSPR(sprn) KVM_INST_SPR(sprn, SPR_FROM)
#define KVM_INST_MTSPR(sprn) KVM_INST_SPR(sprn, SPR_TO)

#define KVM_INST_TLBSYNC 0x7c00046c
#define KVM_INST_MTMSRD_L0 0x7c000164
Expand Down Expand Up @@ -440,56 +434,191 @@ static void kvm_check_ins(u32 *inst, u32 features)
case KVM_INST_MFMSR:
kvm_patch_ins_ld(inst, magic_var(msr), inst_rt);
break;
case KVM_INST_MFSPR_SPRG0:
case KVM_INST_MFSPR(SPRN_SPRG0):
kvm_patch_ins_ld(inst, magic_var(sprg0), inst_rt);
break;
case KVM_INST_MFSPR_SPRG1:
case KVM_INST_MFSPR(SPRN_SPRG1):
kvm_patch_ins_ld(inst, magic_var(sprg1), inst_rt);
break;
case KVM_INST_MFSPR_SPRG2:
case KVM_INST_MFSPR(SPRN_SPRG2):
kvm_patch_ins_ld(inst, magic_var(sprg2), inst_rt);
break;
case KVM_INST_MFSPR_SPRG3:
case KVM_INST_MFSPR(SPRN_SPRG3):
kvm_patch_ins_ld(inst, magic_var(sprg3), inst_rt);
break;
case KVM_INST_MFSPR_SRR0:
case KVM_INST_MFSPR(SPRN_SRR0):
kvm_patch_ins_ld(inst, magic_var(srr0), inst_rt);
break;
case KVM_INST_MFSPR_SRR1:
case KVM_INST_MFSPR(SPRN_SRR1):
kvm_patch_ins_ld(inst, magic_var(srr1), inst_rt);
break;
case KVM_INST_MFSPR_DAR:
#ifdef CONFIG_BOOKE
case KVM_INST_MFSPR(SPRN_DEAR):
#else
case KVM_INST_MFSPR(SPRN_DAR):
#endif
kvm_patch_ins_ld(inst, magic_var(dar), inst_rt);
break;
case KVM_INST_MFSPR_DSISR:
case KVM_INST_MFSPR(SPRN_DSISR):
kvm_patch_ins_lwz(inst, magic_var(dsisr), inst_rt);
break;

#ifdef CONFIG_PPC_BOOK3E_MMU
case KVM_INST_MFSPR(SPRN_MAS0):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(mas0), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_MAS1):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(mas1), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_MAS2):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_ld(inst, magic_var(mas2), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_MAS3):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(mas7_3) + 4, inst_rt);
break;
case KVM_INST_MFSPR(SPRN_MAS4):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(mas4), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_MAS6):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(mas6), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_MAS7):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(mas7_3), inst_rt);
break;
#endif /* CONFIG_PPC_BOOK3E_MMU */

case KVM_INST_MFSPR(SPRN_SPRG4):
#ifdef CONFIG_BOOKE
case KVM_INST_MFSPR(SPRN_SPRG4R):
#endif
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_ld(inst, magic_var(sprg4), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_SPRG5):
#ifdef CONFIG_BOOKE
case KVM_INST_MFSPR(SPRN_SPRG5R):
#endif
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_ld(inst, magic_var(sprg5), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_SPRG6):
#ifdef CONFIG_BOOKE
case KVM_INST_MFSPR(SPRN_SPRG6R):
#endif
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_ld(inst, magic_var(sprg6), inst_rt);
break;
case KVM_INST_MFSPR(SPRN_SPRG7):
#ifdef CONFIG_BOOKE
case KVM_INST_MFSPR(SPRN_SPRG7R):
#endif
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_ld(inst, magic_var(sprg7), inst_rt);
break;

#ifdef CONFIG_BOOKE
case KVM_INST_MFSPR(SPRN_ESR):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(esr), inst_rt);
break;
#endif

case KVM_INST_MFSPR(SPRN_PIR):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_lwz(inst, magic_var(pir), inst_rt);
break;


/* Stores */
case KVM_INST_MTSPR_SPRG0:
case KVM_INST_MTSPR(SPRN_SPRG0):
kvm_patch_ins_std(inst, magic_var(sprg0), inst_rt);
break;
case KVM_INST_MTSPR_SPRG1:
case KVM_INST_MTSPR(SPRN_SPRG1):
kvm_patch_ins_std(inst, magic_var(sprg1), inst_rt);
break;
case KVM_INST_MTSPR_SPRG2:
case KVM_INST_MTSPR(SPRN_SPRG2):
kvm_patch_ins_std(inst, magic_var(sprg2), inst_rt);
break;
case KVM_INST_MTSPR_SPRG3:
case KVM_INST_MTSPR(SPRN_SPRG3):
kvm_patch_ins_std(inst, magic_var(sprg3), inst_rt);
break;
case KVM_INST_MTSPR_SRR0:
case KVM_INST_MTSPR(SPRN_SRR0):
kvm_patch_ins_std(inst, magic_var(srr0), inst_rt);
break;
case KVM_INST_MTSPR_SRR1:
case KVM_INST_MTSPR(SPRN_SRR1):
kvm_patch_ins_std(inst, magic_var(srr1), inst_rt);
break;
case KVM_INST_MTSPR_DAR:
#ifdef CONFIG_BOOKE
case KVM_INST_MTSPR(SPRN_DEAR):
#else
case KVM_INST_MTSPR(SPRN_DAR):
#endif
kvm_patch_ins_std(inst, magic_var(dar), inst_rt);
break;
case KVM_INST_MTSPR_DSISR:
case KVM_INST_MTSPR(SPRN_DSISR):
kvm_patch_ins_stw(inst, magic_var(dsisr), inst_rt);
break;
#ifdef CONFIG_PPC_BOOK3E_MMU
case KVM_INST_MTSPR(SPRN_MAS0):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_stw(inst, magic_var(mas0), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_MAS1):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_stw(inst, magic_var(mas1), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_MAS2):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_std(inst, magic_var(mas2), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_MAS3):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_stw(inst, magic_var(mas7_3) + 4, inst_rt);
break;
case KVM_INST_MTSPR(SPRN_MAS4):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_stw(inst, magic_var(mas4), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_MAS6):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_stw(inst, magic_var(mas6), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_MAS7):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_stw(inst, magic_var(mas7_3), inst_rt);
break;
#endif /* CONFIG_PPC_BOOK3E_MMU */

case KVM_INST_MTSPR(SPRN_SPRG4):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_std(inst, magic_var(sprg4), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_SPRG5):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_std(inst, magic_var(sprg5), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_SPRG6):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_std(inst, magic_var(sprg6), inst_rt);
break;
case KVM_INST_MTSPR(SPRN_SPRG7):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_std(inst, magic_var(sprg7), inst_rt);
break;

#ifdef CONFIG_BOOKE
case KVM_INST_MTSPR(SPRN_ESR):
if (features & KVM_MAGIC_FEAT_MAS0_TO_SPRG7)
kvm_patch_ins_stw(inst, magic_var(esr), inst_rt);
break;
#endif

/* Nops */
case KVM_INST_TLBSYNC:
Expand Down Expand Up @@ -556,9 +685,18 @@ static void kvm_use_magic_page(void)
start = (void*)_stext;
end = (void*)_etext;

/*
* Being interrupted in the middle of patching would
* be bad for SPRG4-7, which KVM can't keep in sync
* with emulated accesses because reads don't trap.
*/
local_irq_disable();

for (p = start; p < end; p++)
kvm_check_ins(p, features);

local_irq_enable();

printk(KERN_INFO "KVM: Live patching for a fast VM %s\n",
kvm_patching_worked ? "worked" : "failed");
}
Expand Down
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